Research into light producing polymers began over a decade ago with the discovery that polyphenylene-vinylenes or PPVs are electroluminescent when sandwiched between two electrodes. Further processing of these polymers has led to the early development of electronically driven organic lasers and liquid crystalline coil block copolymers.
There are efforts to construct efficient luminescent and electroluminescent devices with both high efficiency and light output. The synthetic methodology for the construction of polymers that can be used for applications such as light-emitting diodes, field effect transistors, and photovoltaic devices requires very precise placement of the conjugated units. In these highly conjugated structures the substituents on the aromatic rings can play a key role in the control of the optical and electrical properties of the polymers. It is desirable that the process and components yield end products that have narrowly defined molecular weight distributions and can be synthesized in a controlled fashion.
In order to obtain more electronically efficient structures, copolymers containing alternating PPV blocks have been produced. Unfortunately, these copolymers are either of low molecular weight (MW), or display high polydispersity values that have deleterious effects on the lifetime and usefulness of any device into which they are incorporated. Copolymers with relatively high MW have been reported. However, these copolymers have high polydispersity values (greater than 2 and 3) and are inefficiently produced, requiring several re-precipitations before isolating the final product.
The present invention addresses the above-described problems. The block copolymer compositions of the present invention and those produced by the process of the present invention have desirable properties including narrow molecular weight distributions that are produced in a controlled and reliable manner.